In the first article of several to follow, I will provide an overview of technological advances enabling superior performance in the architectural segment versus historical technologies. In subsequent articles, we’ll expand on these topics, as well as provide an overview and details of emergent waterborne coatings technologies that are closing the gap in the high performance industrial coatings market versus solvent-borne and solvent-less systems.
Many of the technological advances that exist today are the result of increasingly stringent regulations. Volatile Organic Compound (VOC) regulations automatically come to mind first, but there are several others. The elimination of the use of alkylphenol ethoxylates (APE’s) first in Europe in the 1990’s and then in the US, led to new classes of surfactants developed by companies such as Air Products and Chemicals, BASF and others.
Antimicrobial materials lacked global oversight, and even in North America, materials approved in the U.S. were not approved in Canada and vice versa. With the emergence of nanomaterials for applications spanning abrasion resistance, UV-protection, antimicrobial protection and thermal and electrical conductivity, there is a cautious concern that we may not have enough information to deem all of these materials as “safe.” Bioaccumulation and non-degradability add to this concern.
On the VOC front, the latest news comes from China, where exceedingly high airborne particulate and noxious gasses highlighted at the Olympics, accelerated the enactment and strict enforcement of regulations designed to greatly improve the air quality in China, especially in and around large cities.
The encouraging news from China is that, except for small local paint companies, global companies have been addressing VOC limitations for years and can easily leverage their prior work in this geography.
Technological advances have been made in the development of coalescing solvents for waterborne resins that meet the new regulations. Some of these have boiling points that exceed the test protocol and, therefore, are not volatile., A Some approaches include the use of reactive diluents or materials made from plant products (“green chemistry”). Plasticizers, such as most phthalates and n-methyl pyrollidone (NMP), have been replaced with much less toxic materials.
In the preceding years, there has been a preponderance of advancements in waterborne resin technologies. Whereas in the 80’s and most of the 90’s, improvements were typically incremental, in the past few years, they have been very large. Examples of large advancements include core-shell technology, latent crosslinking, 1K technologies that perform similar to 2K, resins with easy-clean properties, resins based on green chemistries, as well as many others. Fluoropolymers, which were once used only in OEM coil coatings, have made their way into other segments of the industrial market, and have some uses in architectural exterior coatings that can tolerate cost to achieve 25+ years’ weatherability. Fluoroadditives for slip and block resistance, as well as mar reduction, have been in production for years. The resins will be discussed in more detail in future articles.
Although not as many advances have been made in pigment technology for the architectural coatings market, there still have been some significant ones. Infrared (IR) reflective pigments mitigate heat, providing as much as 25-30°F reduction in heat vs. conventional pigments in similarly painted structures.
There are new colored pigments that are more colorfast not only in masstones but in pastels. Surface chemistry has improved the weatherability characteristics of TiO2 and inorganic nanomaterials are highly synergistic to organic UV-absorbers and hindered amine light stabilizers (HALS) in exterior semi-transparent stains and varnishes.
In this general category are colorants. Many paint companies have eliminated ready-mix colors in favor of all colors prepared via custom mixing in the store. Therefore colorants had to be reformulated to be VOC-free, in addition to being compatible in both waterborne and solventborne paints and in all types of finishes. This was a particularly difficult challenge due to the high levels of glycols, among other things.
There are a multitude of new additives, including the UVA/HALS mentioned previously. Due to the changing waterborne resin chemistries as well as VOC regulations, additive suppliers have been busy creating chemistries that work as universally as possible.
Defoamers are a good example of a real challenge. Traditional defoamers might include mineral oil or a hydrocarbon carrier with hydrophobic silica and perhaps a fatty amide. They worked well for flat paints, but negatively affected gloss levels in semi- to high-gloss paints and could have a significant impact on the overall VOC level of a finished paint. All things have to be considered in the formulation of a zero-VOC paint.
At about the same time new defoamers were introduced to the waterborne flexographic ink market, there was a need for similar chemistry for different reasons in coatings. Analogs of the flexo defoamers are found in the waterborne architectural market, along with others.
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It is true that the technological advances have been made in the development of coalescing solvents for waterborne resins that meet the new regulations and some of these have boiling points that exceed the test protocol. The technology really create a great impact in our society now adays.